public class Solution {
    public int mySqrt(int x) {
        if(x < 1) return 0;
        long left = 1,right = x;
        while(left < right){
            long mid = left + (right - left + 1)/2;
            if(mid * mid <= x)
                left = mid ;
            if(mid * mid > x)
                right = mid - 1;
        }
        return (int)left;
    }

    public static void main(String[] args) {
        Solution solution = new Solution();
        int x = 85;
        System.out.println(solution.mySqrt(x));
    }
}
